Stone grinding or polishing wheel



Pafentecl May 26, 1941 UNETED STATES PATENT OFFICE STONE GRINDING OR POLISHING WHEEL William Milne, Barre, Vt.

Application July 24, 1940, Serial No. 347,267

v Claims. Cl. 51-209) In grinding and polishing large blocks and slabs of stone it is customary to use grinding and polishing wheels comprising a metallic disc called a cover and a plurality of scrolls depending from the cover, the scrolls usually being formed of cast iron and being secured to the under side of the cover by means of machine screws extending through the cover from the top and threading into tapped openings extending vertically through the scrolls. In use the scrolls rest on the block of stone with the abrasive between the lower edges of the scrolls and the stone. In rough grinding operations the abrasive is in the form of steel shots while subsequent operations are carried out with finer and finer abrasives. By moving the wheel around over the surface of the stone while the wheel is rotating about its axis, the surface of the stone is first ground fiat and smooth. Owing to the centrifugal force imparted to the abrasive by the rotating wheel, the abrasive tends to be thrown radially from the wheel off of the block of stone. Thus it has been customary to build a wall of planks around the stone to catch the abrasive thrown ofi the stone by the centrifugal force imparted to the abrasive by the rotating wheel.

Objects of the present invention are to provide a grinding wheel which has so little tendency to throw abrasive outwardly that it is unnecessary to build the aforesaid wall around the block of stone, which requires less labor in feeding abrasive to it and which is generally superior to the grinding wheels of the prior art.

According to the present invention the aforesaid scrolls are arranged in two, three, four or more sets distributed around the under side of the cover, together with a ring depending from the cover around the sets of scrolls, the outermost scrolls of certain of these sets having inner faces which incline toward the center of the Wheel from their leading to their trailing ends and having forward ends which are tapered and which terminate adjacent the ring, so that abrasive material which is thrown outwardly by the scrolls is caught by the ring and returned toward the center of the wheel by the tapered inclined outermost scrolls. While the ring may be cast in a single piece, it is preferably formed in segments having ends which interfit with each other in overlapping relationship. The scrolls or the ring or both may be cast integrally with the cover but they are preferably bolted to the cover as aforesaid. While the vertical dimension of the ring may be somewhat more or less than that of the scrolls, the scrolls and ring preferably have approximately the same depth. The aforesaid inclination of the inner faces of the outermost scrolls is preferably accomplished by inclining the scrolls instead of tapering them all the way from their leading ends to their trailing ends.

By constructing a wheel in the aforesaid manner the abrasive which is thrown outwardly by the scrolls is caught by the surrounding ring and is fed back toward the center of the wheel by the tapered inclined outermost scrolls whose tapered forward ends extend into close proximity with the inner periphery of the ring, Thus the abrasive does not tend to accumulate against the inner periphery of the ring. Furthermore, it has little tendency to feed under the ring because the ring is concentric with the axis of rotation of the wheel, the inner face of the ring is smooth and the outermost scroll feeds the abrasive away from the ring as soon as it reaches the ring.

For the purpose of illustration a typical embodiment of the invention is shown in the accompanying drawing in which Fig. 1 is a bottom plan view of the new wheel; and

Fig. 2 is a side elevation with parts in section.

The particular embodiment of the invention chosen for the purpose of illustration comprises a cover 0, depending scrolls S, an outer ring R, and a connector K for use in rotating the wheel, the scrolls and ring being secured to the cover by machine screws extending through the cover into tapped openings in the scrolls and rings and the connector K being secured to the cover by means of bolts W. The ring R is formed in four segments, the ends of which overlap and interfit as indicated at R. The scrollsare arranged in four sets, each set comprising six scrolls, With the trailing ends of each set spaced somewhat in advance of the leading ends of the next succeeding set to provide aisles A extending radially between the sets. As shown in Fig. 1 the trailing ends of the scrolls are nearer the center of the wheel than the leading ends so that abrasive which tends to pile up against the inner faces of the scrolls is pushed toward the center of the wheel as the Wheel rotates. The leading ends of the scrolls of each set are approximately in line with the spaces between the scrolls of the next preceding set so that the abrasive which piles up between the scrolls of one set tend to feed under the leading ends of the scrolls of the next succeeding set, the aisles A facilitating the distribuopenings 0. The abrasive is preferably fed under the scrolls through the central opening 0,

either from a hopper or by shoveling. By having the tapered forward ends of the outermost scrolls extend into close juxtaposition to the inner periphery of the ring R comparatively little of this abrasive is thrown radially from the wheel. Thus it is not necessary to build a wall around the block of stone and the abrasive may be fed through the opening 0 at a slower rate. By having the leading ends of the outermost scroll S overlap the outer ends of the aisles A, the abrasive which escapes from between the trailing ends of one set of scrolls and the leading ends of the next succeeding set is immediately started back towards the center of the wheel by the inclined outermost scrolls.

It should be understood that the present disclosure is for the purpose. of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. A grinding wheel for rubbing abrasive material over stone comprising a cover, a. plurality of sets of scrolls depending from the cover, and

a ring depending from the cover around said sets of scrolls, the scrolls and ring having approximately the same depth, the outermost scrolls of certain of said sets having inner faces which incline toward the center of the wheel from their leading to their trailing ends and having leading ends which are tapered to edges which are close enough to the ring to prevent abrasive material to pass between the edges and said ring, whereby abrasive material which is thrown outwardly by the scrolls is caught by said ring and returned toward the center of the wheel by said tapered inclined outermost scrolls.

2. A grinding wheel for rubbing abrasive material over stone comprising a cover, a plurality of sets of scrolls secured to the lower face of the cover, and a ring secured to the lower face of the cover around said sets of scrolls, the outermost scrolls of certain of said sets having inner faces which incline toward the center of the wheel from their leading to their trailing ends and having leading ends which are tapered to edges which are close enough to the ring to prevent abrasive material to pass between the edges and said ring, whereby abrasive material which is thrown outwardly by the scrolls is caught by said ring and returned toward the center of the wheel by said tapered inclined outermost scrolls.

3. A grinding wheel for rubbing abrasive material over stone comprising a cover, a plurality of sets of scrolls depending from the cover, and a ring depending from the cover around said sets of scrolls, the scrolls and ring having approximately the same depth, said cover having an opening through which abrasive material may be fed under the scrolls, the outermost scrolls of certain of said sets having inner faces which incline toward the center of the wheel from their leading to their trailing ends and having leading ends which are tapered to edges which are close enough to the ring to prevent abrasive material to pass between the edges and said ring, whereby abrasive material which is thrown outwardly by the scrolls is caught by said ring and returned toward the center of the wheel by said tapered inclined outermost scrolls.

4. A grinding wheel for rubbing abrasive material over stone comprising a cover, a plurality of sets of scrolls secured to the lower face of the cover, the scrolls inclining toward the center of the wheel from their leading to their trailing ends, and a ring secured to the lower face of the cover around said sets of scrolls, the outermost scrolls of said sets having leading ends which are tapered to edges which are close enough to the ring to prevent abrasive material to pass between the edges and said ring, whereby abrasive material which is thrown outwardly by the scrolls is caught by said ring and returned toward the center of the wheel by said tapered inc-lined outermost scrolls.

5. A grinding wheel for rubbing abrasive material over stone comprising a cover, a plurality of sets of scrolls depending from the cover, and a ringdepending from the cover around said sets of scrolls, the scrolls and ring having approximately the same'depth, the trailing ends of each set of scrolls being spaced circumferentially from the leading ends of the next succeeding sets to afford radial aisles between the sets, the outermost scrolls of certain of said sets having inner faces which incline toward the center of the wheel from their leading to their trailing ends and having leading ends which are tapered to edges which are close enough to the ring to prevent abrasive material to pass between the edges and saidring, said forward ends of the outermost scrolls overlapping said aisles, whereby abrasive material which is thrown outwardly by the scrolls is caught by said ring and returned toward the center of the wheel by said tapered inclined outermost scrolls.

WILLIAM MILNE. 

